Doubts on progress and technology

The ugly side of solar panels

New research shows, albeit unintentional, that generating electricity with solar panels can also be a very bad idea. In some cases, producing electricity by solar panels releases more greenhouse gases than producing electricity by gas or even coal.

Producing electricity from solar cells reduces air pollutants and greenhouse gases by about 90 percent in comparison to using conventional fossil fuel technologies, claims a study called "Emissions from Photovoltaic Life Cycles", to be published this month in “Environmental Science & Technology”. Good news, it seems, until one reads the report itself. The researchers come up with a solid set of figures. However, they interpret them in a rather optimistic way. Some recalculations (skip this article if you get annoyed by numbers) produce striking conclusions.

Solar panels don’t come falling out of the sky – they have to be manufactured. Similar to computer chips, this is a dirty and energy-intensive process. First, raw materials have to be mined: quartz sand for silicon cells, metal ore for thin film cells. Next, these materials have to be treated, following different steps (in the case of silicon cells these are purification, crystallization and wafering). Finally, these upgraded materials have to be manufactured into solar cells, and assembled into modules. All these processes produce air pollution and heavy metal emissions, and they consume energy - which brings about more air pollution, heavy metal emissions and also greenhouse gases.

Energy mix

The ecological burden of energy use depends on the way electricity was generated. Therefore, the researchers bring into account 3 scenarios. One is based on the average European energy mix, another on the average American energy mix (which is about 45% more CO2-intensive) (Note: in this article, “CO2” stands for CO2-equivalents which means other greenhouse gases are included). A third scenario uses the figures of the recent “CrystalClear” European Commission project, which investigated the real energy mix used by 11 European and American silicon and PV module manufacturing factories. Since they use comparatively more gas and hydropower, this is the best case scenario. The researchers investigated 4 types of solar cells: multi-crystalline silicon (with an efficiency of 13%), mono-crystalline silicon (14%), ribbon silicon (11.5%), and thin-film cadmium telluride (9%).

"The optimistic conclusions of the researchers are based on a life expectancy of 30 years and solar insolation in the Mediterranean"

The scientists come up with figures concerning the amount of greenhouses gasses emitted per kilowatt-hour of electricity delivered by one square meter of solar cells. They do that for every type of cell and for the three different scenarios. Thin film solar cells get the best score with 20.5 grams of CO2 in the European energy mix and 25 grams of CO2 in the American energy mix. In spite of their lower efficiency, they are more eco-friendly because they need less material and no aluminium frame. In spite of their high efficiency, mono-crystalline silicon cells score worst, with 43 grams of CO2 in the EU, and 55 gram of CO2-equivalent in the US. All other types and scenarios fit between these two extremes.

Solar insolation

However, these conclusions are dependent on some assumptions, most importantly solar insolation (the amount of sunlight that the cells receive) and lifetime expectancy. For solar insolation, the researchers choose 1,700 kWh per m² per year, which is the average of sunlight in Southern Europe. For lifetime expectancy, they choose 30 years. From these variables, they calculate the total lifetime electricity generation of one square meter of solar cells. Next, they divide the amount of CO2 emitted for the production of one square meter of solar panels by this lifetime electricity generation – and that’s how they achieve their conclusions.

"Surprisingly, the key data of the calculation (the amount of CO2 emitted per square meter of solar panels) are nowhere to found in the report"

Surprisingly, the key data of the calculation (the amount of CO2 emitted per square meter of solar panels) are nowhere to found in the report. That’s remarkable, since these data are the most objective numbers available. Even so, they can be calculated by multiplying the obtained results (in gram CO2 emitted per kilowatt-hour of generated electricity) by the lifetime electricity generation. This calculation gives the amount of greenhouse gases emitted for the production of one square meter of solar panels, regardless of the assumptions on solar insolation and lifetime expectancy.

2 to 20 flights

Once calculated, it's not so suprising that the researchers choose not to write these figures down. In the best case scenario, one square meter of solar cells carries a burden of 75 kilograms of CO2. In the worst case scenario, that becomes 314 kilograms of CO2. With a solar insolation of 1,700 kWh/m²/yr an average household needs 8 to 10 square meters of solar panels, with a solar insolation of 900 kWh/m²/yr this becomes 16 to 20 square meters. Which means that the total CO2 debt of a solar installation is 600 to 3,140 kilograms of CO2 in sunny places, and 1,200 to 6,280 kilograms of CO2 in less sunny regions. These numbers equate to 2 to 20 flights Brussels-Lissabon (up and down, per passenger) - source CO2 emissions Boeing 747.

According to the researchers, producing the same amount of electricity by fossil fuel generates at least 10 times as much greenhouse gasses. Checking different sources, this claim is confirmed: 1 kilowatt-hour of electricity generated by fossil fuels indeed emits 10 times as much CO2 (around 450 grams of CO2 per kWh for gas and 850 for coal). Solar panels might be far from an ideal solution, but they are definitely a better choice compared to electricity generated by fossil fuels. At least if we follow the assumptions chosen by the researchers.

Northward

Logically, if we make the same calculations for a solar insolation of 900 kWh/m² (the yearly average in Western Europe and in the Northeast and Northwest USA), the results get worse. In the worst case scenario (US grid, mono-crystalline silicon), emissions rise to 104 gram CO2 per kilowatt-hour of solar generated electricity, which makes solar panels only 4 times cleaner than gas. Now let’s play a bit with the life expectancy.

If we combine this lower solar insolation with an expected lifetime of only 15 years, the worst case scenario becomes 207 grams of CO2 per kilowatt-hour – just 2 times better than gas. Agreed, this is the worst case scenario, and even in that case solar panels are still a better choice than fossil fuels. But it becomes quite hard to describe them as a “clean” source of fuel.

This map (click to enlarge) shows the amount of solar energy in hours, received each day on an optimally tilted surface during the worst month of the year. For a more detailed view of solar insolation (in kWh/m²/yr) see the links above.

"A better strategy would be to use already available solar panels to produce more solar panels"

The life expectancy chosen by the researchers is, well, just an expectation. It’s true that most manufacturers give warranties of 20 to 25 years, so technologically speaking a life expectancy of 30 years is not implausible. However, there are other than technological reasons that may lead to a significantly lower life expectancy. The scientists note that the environmental score of solar panels will improve, because they are becoming more efficient each year. (They also become thinner, so less energy is needed to make them). Most likely they will also become cheaper.

Life expectancy

That means that in 15 to 20 years time, if the evolution in efficiency carries on the way it does now, a solar panel with an efficiency of 10 percent produced today will have to compete with cheaper solar panels that have efficiencies of about 20 percent. Moreover, and that’s a fact that the researchers are not taking into account, solar cells degrade in time. Typically, the warranty given by solar cell manufacturers covers just 80 percent of power output. All this means that it may make economic sense to substitute older panels with newer panels before they are 30 years old. Again, even in that case the ecological score will probably still be better than the one of fossil fuels, but the point is that the gap can become very small.

For rooftop and ground-base installations, the eco-friendliness can be good or doubtful, depending on the solar insolation and the life expectancy. But if we consider solar panels mounted on gadgets like laptops or mobile phones, solar energy becomes a plainly bad idea.

If we take a life expectancy of 3 years (already quite optimistic for most gadgets) and a solar insolation of 900 kWh/m² (quite optimistic too, since these things are not lying on a roof), the result is 1,038 gram CO2 per kWh in the worst case scenario (high-efficient mono-crystalline cells produced in the US). That means that it is better for the environment to power a gadget with electricity generated by coal, rather than by a solar panel.

First, solar cells are far from a zero emission technology. Two: solar panels can be a doubtful choice in less sunny regions. Three: solar panels mounted on gadgets are completely insane. Four: solar cells should be recycled. Five: some law or incentive should be introduced to guarantee a life expectancy of 30 years. And if possible, solar thermal power should have priority over solar PV power.

"All this does not mean that PV solar energy should not be promoted. But some facts have to be faced"

It should be realized that solar panels first raise the amount of greenhouse gasses before they help lowering them. If the world would embark on a giant deployment of solar energy, the first result would be massive amounts of extra greenhouse gasses, due to the production of the cells.

Solar photovoltaic (PV) systems and their manufacturing become more efficient over time, so you would expect that the situation has improved since 2008. However, things got worse. This is largely due to the relocation of manufacturing to China, where the electric grid is twice as carbon-intensive and 50% less energy efficient.

The typical solar PV power installation requires access to a private roof, and a big budget. However, wouldn't it be possible to get around these obstacles by installing small solar panels on window sills and balconies, connected to a low-voltage direct current (DC) distribution network? To put this theory to the test, I decided to power Low-tech Magazine's home office in Spain with solar energy, and write my articles off the grid.

Low-tech Magazine makes the jump from web to paper. The first result is a 710-page perfect-bound paperback which is printed on demand and contains 37 of the most recent articles from the website (2012 to 2018). A second volume, collecting articles published between 2007 and 2011, will appear later this year.

Comments

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Very interesting article indeed… Even when "The ugly side of solar panels" is maybe a little extreme, it is true that the carbon footprint of manufacturing any piece of technology cannot be neglected.

Maybe I've skipped over some section, because even when I think I understand the logic for no solar panels in gadgets (low efficiency of small panels, while manufacturing cost increases per square cm), maybe it should be more explicitly expressed.

Efficiency and size don't matter. The problem with gadgets is their short life expectancy and the amount of solar insolation they receive. It takes some years before a roof-top mounted solar panel delivers as much energy as was needed to produce it. This so-called "energy payback time" depends on the type of solar cell and the amount if sunlight it receives. The problem with gadgets is that they don't receive much sun (they are not mounted on a roof to absorb all available light) and thet their life expectancy is at best 2 or 3 years. That means they will be discarded before the solar cell had the chance to produce more energy than was needed to produce it.

That's not the only "ugly side" so solar panels. I am a great believer in the benefits of solar energy and other alternatives to oil, but a recent journey through Southern Germany made me think. Many picturesque old villages around the Bodensee are now defaced by huge shiney dark-blue panels. Whole farmhouses have been hidden behind them. Surely someone could pay a little attention to the aestetics of things. Just because it's "Good for the Earth" doesn't excuse "Bad Taste". Please will someone look into alternatives? Say - slate grey, terracotta bronze?
Just plastering our world full of ugly blue sheets is not the answer. :(
Martin

"Style remains a matter of taste". I am German, and I know the are around Bodensee. Its one of the most beautiful places in Germany. I do not see the solar panels as an disadvantage, in terms of messing up the scenery. I rather see it as an advance in time. Want to have some wood/clay/tarsheet tiles to absorb or reflect the light, or to use it wisely to regain the energy? Mr. Cleaver, its your brain playing a trick on you. What you consider nice, might appear dirty to others. Apart from that, there are other type of solar panels coming up. Translucent ones as brown/red and black are available. Only a matter of time.

The article seems quite one sided. Comparing the "worst case solar scenario" (old panels, bad location, little use) to best case gas. And still points out that it would only be twice as little CO2. Trying to write good things to be bad. Imagine a car would produce 50g of CO2 instead of 100g, by giving the same distance and power of engine... It would be a breaker...

Before jumping to the conclusion that gadgets should be "powered by electricity from coal," I think one needs to examine the CO2 costs of the *batteries* almost all gadgets use to store power. And the often-inefficient transformers that are used to charge those batteries. For a desktop calculator, at least, the PV modules are often *in place* of batteries. If other devices can have smaller batteries by adding solar panels for more frequent recharging, the CO2 cost might go down ... probably not enough to pay itself back in the three-year lifespan of the device, but perhaps bringing it out of the "insane" level.

Maybe most gadgets with PV have the same size batteries as if they had no PV, but to assume that you can attach a coal plant directly to your cellphone (or even to a land line telephone, which has lots of batteries at the telco) seems like jumping to conclusions too quickly.

I don't have PV on my house yet ... first has been a reduction to 60 kWh/mo of electricity, now is installing a 1.6 GPM shower head, and next will be a solar thermal collector to heat the house and water (I still consume at least 10 therms of gas each month in the cooler months).

Its great to see both sides of an arguement. I generally agree with the conclusions, but I think we should consider the longer term future and not focus so much on current limitations of what is still a relatively immature technology.

As with any new technology, PV will become more efficient, cheaper and cleaner to produce. In order for this to happen we (Governments / NGOs / Individuals) need to invest more time and money into making PV viable, e.g. through regulations, technical standards, R&D, manufacturing processes and generating consumer demand.

As more electricity is generated from PV (and other renewable sources), the manufacturing of such technology will become less carbon-intensive.

In terms of using PV for gadgets, I agree its difficult to justify over such a short life expactancy. However, this will change as manufacturing costs / carbon emissions decrease and efficiencies increase. I do have a problem with the manufacturers of these gadgets as they intentionally design their products to last such short periods - this is where regulations should be put in place for increasing life expectacy and making the manufacturers responsible for the disposal of 'old' products.

A message to the guys at fark.com, calling me an "idiot" and an "asshole" :

Obviously, some of you didn’t get further than the three first words of the headline. I did not write that solar panels are a bad idea (except for gadgets), nor that we should burn coal or build more nuclear plants instead. However, being an advocate of solar energy myself for years, I was shocked by the amount of energy needed for the manufacture of one square meter of solar cells – and by the fact that the authors of the study try to hide that. Yes, solar energy is the future, among other renewables, but I think these figures show that it might be better to use solar panels where there is as much sun as possible. In deserts, solar insolation can be 6,000 kWh/m²/yr, and more. That makes solar cells 40 times more eco-friendly than burning fossil fuels.

Having followed the solar industry for over 40 years, I'll make a few observations. First, solar thermal for large installations is 2-3 times as efficient as photovoltaics AND uses far less materials. It is also very easy to build energy storage into thermal systems. Second, there is a class of gadgets where photovoltaics is just about perfect. Those are remote sensing and sparsely populated operations. The solar panel/cell phone/gell battery kiosk for emergancy phones is a good example of the latter. Installing them along I5 in California cost 1/4 as much as a wired system and that included building the cell towers and relays.

In the middle ground, powering homes and businesses, the cost effectiveness of solar depends strongly on the ability to push excess power back into the grid. Home power loads are seriously out of sync with supply. My peak loads are at night in mid-winter. At noon in the summer, I need almost nothing.

"... Overall, all PV technologies generate far less life-cycle air emissions per GWh than conventional fossil-fuel-based electricity generation technologies. At least 89% of air emissions associated with electricity generation could be prevented if electricity from photovoltaics displaces electricity from the grid."

What's the use of sending me this link? It's the same page that I am linking to in the article, it's the same study we are talking about here. So what's your point then? Just believe whatever the experts say and shut up?

I think that you should check your calculations. They looked a bit suspect to me because the amount of energy used to make the panels would cost more than the wholesale price of panels. So I checked:

Looking at the best case scenario, you say that a square metre of solar panel will cause 7,527 kg of emissions, given an emission intensity of 20.5 g/Kwh. That implies that the panel generates 7,527/0.0205 Kwh over its 30 year life time (the 30 years comes from the study).

7,527/0.0205 Kwh = 367,170 over 30 years.
That's 367,170/30 = 12,239 Kwh/ year - not bad, but sadly not possible given a solar intensity of 1700 Kwh/year.

Unfortunately, that does not change the conclusions of the article, since I overestimated both C02-emissions and electricity generation.

But it does mean that the number of intercontinental flights is hugely overestimated. The C02 cost of 1m² of solar panels is not (in the best case scenario) 7,527 kg but 75 kg. And in the worst case scenario it is not 31,416 kg but 314 kg.

Rushing through the article, I reflect on the idea that solar cells might become dramatically cheaper to produce in a few decades due to materials research and production technologies. Solar cells tend to diminish output over time, but still can be productive with a fractional output. They might be useful for hundreds of years if sufficient real-estate exists to recycle them as low-yield units where possible. Design technologies already exist that greatly extend the output of cells, by external focusing of sunlight on cells and the use of susbstrate cooling systems. I remember a member of my computer club some thirty years ago who went on to wealth and fame in part for his self-focusing cell systems that achieved a record for output for given parameters (Midway Labs, 1980's). Unfortunately, Paul Collard did not fully appreciate the importance of cooling systems to preempt premature aging and his systems succumbed to declining output in only a year or two. However, new experimental systems are promising. Don't write them off completely. You might be disappointed.
Lots of research:http://www.redrok.com/main.htm

Ron: everybody makes mistakes. The fact that I fess up, might be a reason to trust me and accept the conclusions that stand up. If not, prove me wrong.

The scientists come to their conclusions starting with a solar insolation of 1700 kWh/m²/yr and a life expectancy of 30 years. You don't have to be a mathematician to conclude that the results are 4 times worse when you halve both the solar insolation and the life expectancy.

I saw quite some blogs and science magazines just posting the 89 percent advantage of solar energy, because they did not bother reading the paper. At least, this news should be accompanied by the fact that it is based on two subjective assumptions, no?

Actually, having worked in the semiconductor industry, I was happy to see somebody perform this analysis. I always wondered if the energy going into producing those solar panals was more than what came out. I was actually worried that they might take more energy to make them than they produce! Fortunately this turned out not to be the case -- but there are other concerns. Manufacturing of the panels does use huge amounts of water (this depends on the specific process used to make the panels, but it could be as high as a 1000 gallons per sq. ft. Also, there are a host of toxic chemicals used in the proces as well which might make solar less attractive. Of couse, non VC based systems are much better over all.

Speaking of toxic chemicals -- there is a story on Grist linking to this page and to an article in the Washington Post, called "Solar energy firms leave waste behind in China". An excerpt:

"Because of the environmental hazard, polysilicon companies in the developed world recycle the compound, putting it back into the production process. But the high investment costs and time, not to mention the enormous energy consumption required for heating the substance to more than 1800 degrees Fahrenheit for the recycling, have discouraged many factories in China from doing the same."

As one reader comments on Grist: "This is not a problem of technological feasability but of social irresponsibility. This isn't like nuclear energy which produces a waste no tech can deal with".

And that's correct, but it shows again that PV has potential negative sides, and they should be accepted if we want it to be a solution instead of a new problem.

Kris De Decker exhibits great ignorance about PV technology and life cycle impacts with his comments. The study in ES&T that he cites, undertook year-long independent expert peer reviews before it was accepted for publication by this most prestigious journal. Just a couple of remarks to some of his points that deserve an answer. Degradation losses of 0.5% to 1% /yr are included in our studies; the low number is confirmed by utility (e.g., TEP, AZ) records and the utility posts on the web daily perfomance of their biggest plant Springerville). The numbers of gCO2/kWh that De Decker (is this a real name?) demonizes us for not showing!! are intermiadiate numbers in a LCA. The final numbers with which PV can be compared with nuclear and fossil are g CO2/kWh. The former can easily be backcalculated from the later.
His assumptions about 3 yr life expectancies are rediculous. PV flat modules have confirmed lifes of 30 yrs and their structures can well last 60 yrs, but consevatively, we used 30 yrs for both.

The conclusions of your study are that “at least 89% of air emissions associated with electricity generation could be prevented if electricity from photovoltaics displaces electricity from the grid”.

That is a deceptive message since it implies a solar insolation of 1,700 kWh/m²/yr, which is everything but self-evident. Germany, for example, the world leader in solar PV power, has much less sun than that.

If I would have been one of those expert peer reviewers, I would have advised you to attach the following sentence to your conclusions: “...if the solar insolation is 1,700 kWh/m²/yr”. You know damn well that most media don’t get further than the summary.

The 3 year life expectancy mentioned in the article concerns gadgets like mobile phones and laptops, not rooftop panels. You should read the text carefully.

If you would read more than one article on this website, you would realise how ridiculous your accusation sounds. You, on the other hand, are paid by the renewable energy industry.

And if you send cowardly comments like this without mentioning even a pseudonym or an e-mail adress, you should remember that your ISP shows up in the web traffic analysis - especially relevant when you send "anonymous" comments from the server at your job.

Renewable Energy Manufactures/suppliers should use their own product to manufacture.

The manufacturers’ of Solar Panels and other forms of renewable energy with related support products manufactures/suppliers - should have at least the decency to practice what they preach what they market to the public.
That would be the best marketing approach I can think off.
If they believe in the product, they should utilize it to its fullest potential.
It will give the manufacturer the actual experience of utilizing the product on a daily basis, view and experience any improvements that are needed, implement the improvements and capitalize on that improvement to improve the product and its performance.
This will instill confidence in the public to purchase the product.

While this article has some valid points, its arguments are now obsolete. Using a new nanotechology based ink, NanoSolar corporation is producing 100's of feet of solar panel per minute. No foundries, no highly toxic metals. No need for huge amounts of energy consumption (CO2) like with crystalline silicon cells. The new ink based panels cost a tiny fraction of silicon. This technology is going to change the world as we know it.

I've built solar panels by hand and while I can't vouch for the numbers in this article, there are most certainly environmental negatives that come with using silicon cells. I was poisoned when I handled silicon cells without gloves and I'm still dealing with the effects of that experience.

Great article, glad to see it, don't let the DAs get you down. I too am an enthusiast for sustainability who is critical of thoughtless cheerleading. Photovoltaics are, unfortunately, a sexy but less-than-perfect answer, as is wind. There are those who like to see the world in a black-and-white, us-vs-them, all-or-nothing mindset, be it for their favorite political candidate, their environmental cause do jour, or their energy solution.

Having just visited Germany, I can tell you that things are worse than you make out here. I don't agree with Martin that the blue panels deface (I think they're kind of cool looking against the traditional reds and browns), but I did see lots of people planting them on their ultra-steep roofs (much more than the latitude) and pointing them in whatever direction the house seemed to face on the street side (north, east, south, whatever). I think the goal was to impress the neighbors rather than to generate energy, and why not? The government is paying for it! I asked a friend if he knew how many cloudless days they got - it happened to be overcast with high clouds at the time and he (only partly in jest) said, "You mean sunny like this? Because this is as close as it gets."

Fascinating argument back and forth for a lay person such as myself. I was simply googling for manufacturing articles for solar as a prospective business to get into. Wow! What a summation of information. Thanks for sharing.

I would suggest we give a good long studied look into the energy production values of how a magnetic spinning disc could generate energy uinto a generator similar to the ones that wind turbines are generating but with higher friction values for higher electric output from the powerful spin that can be caused by rare earth magnets in specific allignments

On average, stateside PV manufacturing in a worst case scenario the CO2 payback is 4 years (best case: less than 1 yr for thin films). The total-energy payback is around 7 years. In other words, all energy produced by any 7 yr old PV system is produced without any negative environmental impact.

For more info please read some detailed analysis done by qualified and very careful experts. All you have to do is google "solar co2 payback".

Thanks for noting me. I use Firefox myself and I have no problem posting comments here. But you are the second to report this, so I will try to find out what is wrong.

Concerning your criticism on the article: I have analysed a scientific study that everybody can verify (although they put it behind a paywall in the meantime) and you counter my analysis with a search command in Google? Come on.

If there is one thing you should have learned from my analysis it is that every conclusion considering the energy payback time of solar panels depends on the chosen solar insolation, which is absent in your conclusion of the "detailed analysis done by qualified and very careful experts".

Thanks for the additional information. However, I am clueless on why I should change the conclusions of the article. I see no contradictions between my conclusions (which are entirely based on the figures of the researchers, these are not "my" numbers) and yours.

For instance, your second source also builds upon a solar insolation of 1,700 kWh/m², so again the energy payback time would be doubled if you choose 900 kWh/m². Same goes for the life expectancy. By the way, nowhere in the article I give any figures for the energy payback time of solar panels, I compare with electricity produced by gas and coal.

Actually the very first resource I supplied, the one that was a doctoral thesis, was a study done on the insolation in Ohio, a very non-optimal solar situation. A far more aggressive analysis then your back-of-napkin thing. What motive would he have to paint a rosier-than-reality picture ... especially when it's going to get torn apart by his professors? If you've spent time in academia as I have you'd know he'd be stupid to do so. And it comes out with a CO2 payback of 3.7yrs, and 7 for total energy. The Swiss study is jsut as objective, showing that in China where they throw environmental caution to the wind it may never environmentally pay for itself, but clearly show how it can be brought down (and will be - for economic reasons) to 4 yrs. Of course,

But the idea that any one of the references I gave you feel in flawed invalidates all the other references simply doesn't follow reason. These are independent analysis done from widely different perspectives, backgrounds, and motivations.

I think you're on the right track with leveraging low-tech whenever it is superior, but you fail to realize that solar energy is really very low-tech ... it's just a big diode - the simplest electrical device in the world.

But turning the goo in the ground into gasoline with all it's high-tech additives, the dealing with all the waste and turning it into useful stuff through tons of processing with sulfur and all it's CO2 heavy logistics ... that my friend is a lot more complicated, and you suggest it's better than building a diode that spits out energy for 25+ years or more? Well, it's your website so I'm not going to insult, but your positions speak for themselves, whether they're good science are absurd.

Dave, I don't understand why you react this way. I appreciate a lot the links you have given us, these are indeed very well researched analyses and I am very happy with them (especially since the study I have based my story upon has meanwhile disappeared behind a paywall). But, again, there is no reason why these studies should make me change any number or conclusion in my article. You keep talking about CO2 payback times, but that is not the subject of my article, these figures are nowhere mentioned.

By the way, the author of the study I critized commented on this article, see below, and even he did not dispute my calculations. He just cursed me for making them.

You have been reading (and commenting on) many more articles on my website, so your assumption that I prefer fossil fuels to solar energy is rather strange. I criticize solar energy standing from the other side: for me, it is not green *enough*. Of course fossil fuels are worse, and that is stated clearly - several times - in my article.

The doctoral thesis you appreciate so much - and rightly so - gives a figure of 5,589 kWh of embodied energy per 1 kW of rated output of the modules produced. My God, Dave, that is an afwul amount of energy! With it, you can power a 300 watt flat screen television for 800 days, 24 hours per day! Of course, over the years, the solar panels will generate more energy than that, but don't call them a clean energy source. They are just somewhat better than fossil fuels, and how much exactly depends a lot on where they are placed and where they are produced.

Thanks for the calculations and the back-and-forth dialog. (I especially like the hypocrisy of the guy from DC Power Systems anonymously saying you must be a shill for Big Oil).

One question that was asked below and wasn't answered:

You say that PVs on gadgets is insane because the energy used to create the PVs is more than the total energy produced over the lifetime of the product. But this is only half the story, because gadgets without PVs require more batteries to be manufactured and more energy to fill those batteries.

(PS: Same bug with posting is happening. I'm on FF after having been on this page for a long time. I'm now refreshing and trying to post quickly.)

The question isn't whether the PVs will produce more energy than was used to create them, but whether, all things considered, a gadget with PVs consumes less energy than a gadget without.

Do you have any figure for the energy that goes into a gadget with a three-year lifetime, consuming multiple batteries, each of which has to be made and charged?

Sam, that's a good remark, but I don't think it would make much difference. You will require almost as much electricity from the grid as with a normal gadget, because the solar panel will not generate much energy (unless your phone is lying in the sun all day, which seems not so practical to me).

Also, I am not sure why a gadget with a solar panel would need less batteries during its lifetime? If I understand it well, the solar cells charge the battery, not the gadget itself directly. And if it would, then to answer your question we need figures that give the embodied energy of a battery. Until today, I have not been able to find a life cycle analysis of a battery, whether it's batteries for gadgets or batteries for electric cars.

It should be realized that the energy consumed for the production of photovoltaics is minuscule compared to the world's energy consumption and the energy consumed for the production of solar hot water capacity is even lower.

Thinfilm PV is requires 20 MJ per Watt:
tiny.cc/R5rRB

and keeps dropping:
tiny.cc/N5zHy

But let's say you want to cover 20% of the world's electricity demand in 25 years with PV. And let's say PV has a capacity factor of only 15%. Therefore you need 2.5 TW of PV in 25 years to cover 20%. That's 100 GW per year.
tiny.cc/jqME2

The world consumes 500 EJ per year. So in order to produce 100 GW of thinfilm PV per year, you need 0.4% of the current world's energy consumption.
tiny.cc/bvmzi

And the 0.4% production energy needed to produce new thinfilm PV panels will obviously and entirely be covered by the thinfilm PV in a relatively short time compared to the 25 year warranty of the PV panels produced.

Anyone: thanks for the links. This page now must contain every life cycle analysis of solar panels ever written....

But, I have to make some objections regarding your conclusions. You rightly state that it takes around 3 times less energy to produce thin-film solar cells, but you should also mention that their life expectancy is around 3 times less. So in the end, the result is the same. Maybe even worse, because you have to install the arrays 3 times instead of just once.

Concerning your general conclusion: you calculate that generating 20 percent of the world's electricity demand only requires 2 EJ while the world consumes 500 EJ. But you should compare apples with apples. This 500 EJ is worldwide energy consumption, not worldwide electricity consumption. Electricity consumption is only a small part of energy consumption, around 15 percent. And then you take only 20 percent of it.

The main study you refer to is very interesting, especially when they talk about how embodied energy of solar panels is calculated. Although it dates from 1998, this is definitely a paper I will use for further reference.

The researchers also confirm the findings above; they state an energy payback time of 4 to 8 years under 1,700 kWh/m² irradiation for a grid connected roof system. Make the same calculation for 800 - 900 kWh/m² and energy payback time is 16 years in the worst case scenario, not far from the guaranteed life expectancy of 20 years. Again, this is not to say that solar is by definition a bad choice, far from that. But, their figures confirm that not so good placed panels placed in a not so sunny region might have a doubtful or no advantage.

Very interesting is also that the researchers include the embodied energy of the lead-acid battery in one of their scenario's, the stand-alone solar home system. I did not think of that before. If you include the embodied energy of the 4 lead-acid batteries required over a 20 year lifetime of the solar panels, the system has a negative energy payback time under a solar irradiation of 800-900 kwh/m²/yr.

And of course you have compare PV production energy requirements with the total world's energy consumption and you have to compare it with the world's total deforestation and you have to compare it with the world's total methane production due to the current and raising meat consumption!

After all your statement is that if photovoltaics would be built in large numbers the greenhouse gas emissions would go up significantly! But obviously this is not the case as you can clearly see based on the fact that greenhouse emissions from other sources are many orders of magnitudes higher than from PV, even if you take old data and produce PV in large number on old inefficient equipment and do ignore the simple fact that PV electricity production replaces fossil fuel based electricity production!

And my example of replacing 20% of the entire electricity production with PV within the next 25 years is ABSOLUTELY HUGE and would most likely NOT happen anyway! Keep in mind the entire world's hydro production is currently at 16%!

Given the massive advancement of PV mass production technology in the last 5 years, it does make no sense to take 11 year old data from inefficient production equipment, which was largely based on IC production equipment and not specifically designed PV mass production equipment!

I took an old example to show you how small the energy consumption is, even if you were to build 100 GW per year! Worldwide PV installation last year was only 5.5 GW! Worldwide PV production 1998 was probably 0.01 GW.

It is useless and unfair to compare PV production energy requirements with deforestation and meat consumption. Because then you are talking about greenhouse gases and in your calculation you were talking about energy requirements. And by using exactly the same logic you might as well argue that greenhouse gases from coal plants are not such a big deal because deforestation and meat production are worse...

As for your second remark: I have noticed that most PV modules are connected to the grid, yes. But, I hope that you have noticed that if everybody would be using PV modules and they would all be hooked up to the grid, there would be no energy at all at night? Grid-connected solar systems can only work if you have a backup of fossil fuel energy plants. If you want to do away with fossil fuels, then you have to imply some kind of energy storage - and thus ultimately include the embodied energy of this energy storage system in the whole picture.

And even though I came up with an 11 year old study and assumed 100 GW of new PV every single year, I still came up with an insignificant greenhouse gas production. And this is what this is all about.

Coal power plants are obviously a big deal because they are producing 50% of the world's electricity and not less than 1% like PV does!

And coal power plants not only produce CO2 during their construction, coal mining and coal transportation, they mostly produce it because they burn coal!
And PV does NOT burn coal to produce electricity!

Since electricity consumption during day time is up to 3 times higher than at night, PV will obviously reduce the load on the grid and will reduce the fossil fuel needed for electricity generation!
And I only calculated with 20% PV for good reason.

Actually, hydro power lakes are currently pumping up coal and nuclear power every single night to be able to produce more power during day time! If more PV is produced, less electricity needs to be pumped and wasted at night because more power is produced during daytime thanks to PV.

--> "And coal power plants not only produce CO2 during their construction, coal mining and coal transportation, they mostly produce it because they burn coal! And PV does NOT burn coal to produce electricity!"

This does not matter, this distinction you make has no use whatsoever. For instance, take the solar home energy system that uses 4 batteries over its lifetime and has a negative energy payback under a solar irradiation of 800-900 kwh/m²/yr. (I know, worst case scenario, but I want to explain something).

Never in its lifetime it burned coal to produce electricity, according to your definition. All its energy consumption is embodied energy - but this was generated by coal, too. If such a system has a negative energy payback, this actually means that it would have been a better choice to power your home with electricity generated by a coal plant than with electricity generated by a solar panel which was produced with energy generated by a coal plant.

What counts is total energy consumption: embodied energy + energy consumption during the use phase. If energy consumption during the use phase is zero but embodied energy is high, a system can still consume a lot of energy, although it does not seem to be that way.

--> "Coal plants mostly produce CO2 because they burn coal!"

Exactly. And solar panels and batteries produce CO2 because they (are produced by energy-instenive manufacturing methods that) burn coal.

Of course it matters, whether you build a new coal power plant and a new coal mine and burn lots of coal or whether you build new PV modules and do not burn coal at all.

And your solar battery combination dream will never happen, because batteries are simply too expensive and not needed anyway, because PV will reduce the load on the current grid.

Again, fact is that thinfilm PV modules do not use energy intensive manufacturing methods and if one produces lots of them, the fossil fuel portion in the electricity grid will obviously be reduced, because most people actually install PV modules on roofs to produce electricity and not in their basements for fun.

Fact is, the more PV modules are built, the less CO2 is produced during the production of future PV modules.

Sounds to me like the researchers you are critical of had a more objective spin on the data than you have. Your map clearly shows that southern Europe is typical of most of the US land area. And your final paragraph upends your entire argument. The solution is to get on solar and other renewable energy sources as soon as possible so that we can build the rest of our renewable energy system using low carbon energy sources. An honest calculation would compare the CO2 emitted by waiting to go to renewables with the CO2 emmitted by going to them as soon as possible. In the next century we have to go to renewables, and there is not enough energy to go to renewables without relying heavily on solar. The only question is when. And there is just no 'ugly' side of solar energy when honestly compared with the other options. The only drawback is seen by the shortsighted who note that it costs now rather than deferring the costs to our grandkids.

--> "Your map clearly shows that southern Europe is typical of most of the US land area."

So what? Firstly: I am not an American, I live in Europe, this is an international website. Secondly: The study I criticized analysed the situation both in Europe and in the US and its conclusion was not tied to a certain region or country (which is my main criticism and shows that they are not objective). Thirdly: By far most solar panels worldwide are installed in Germany, waaaaaay north of Southern Europe.

--> "And your final paragraph upends your entire argument. The solution is to get on solar and other renewable energy sources as soon as possible so that we can build the rest of our renewable energy system using low carbon energy sources."

This is the solution that I have put forward, yes. I describe a problem, and give a possible solution, what's wrong with that? But, name me one solar manufacturer that fabricates its products by means of solar energy? Using solar panels to produce solar panels is the way to go, but it does not happen. We use them to power an ever growing plethora of energy-sucking gadgets - and this will not get us anywhere.

You make it sound like I want to stick with fossil fuels and that is plain bullshit. I advise you to read the article and the comments again.

What about if you try to store the solar energy? In Germany, the world leader in solar, they feed it back into the grid when they're not using it, but they get only 1% of their power from solar. If everybody did that it wouldn't work, since their is no power at night and little in the winter, evening, morning, and when it's cloudy. You've got to store it, and the cheapest way to do that is lead-acid storage batteries. A single gallon of gasoline contains as much energy as one ton of lead-acid storage batteries! In other words, to make the batteries would take a huge amount of energy, and storage would lower the efficiency of the use of the energy. In other words, solar would probably have something like five or ten times the carbon footprint, making it perhaps comparable to coal-fired power, at about 100 times the cost. What a joke.

Hello,
Interesting analysis. It is reasonable to try to see the complete scenario. Though, I was wondering if you took into account the energy needed to produce turbines, generators, furnaces, water and steam pipes, valves... but again you would need to take into account the energy required for a facility producing solar panels.

Moreover, there is energy loss involved in transporting electric energy... Having the energy produced into your own home would definitely be more efficient as regards energy transportation.

This is not a black and white issue but I do have to say that no solution will be perfect until we reduce our energy consumption and find more efficient technologies. Not an easy task but this has to happen first.

The article seriously over-states the amount of energy embodied in solar panels. A polycrystalline panel, over an expected 30-year lifespan, will produce 10-20x the amount of energy that goes into its production (starting with the mining of the raw silicon dioxide for the cells and the bauxite for the frames, through the final assembly and distribution). That the author is using innacurate information can be easily demonstrated by looking at the economics: a typical 200W polycrystalline panel mounted facing south at about a 30-degree pitch in, say, Pennsylvania, will produce about 220 kWh per year or about 5,500 kWh over a 25-year lifespan (most panels are expected to last over 30 years). At an average electric cost in the US of about 10 cents/kWh, that's $550-worth of electricity. That 200W panel will sell wholesale for about $450. The total cost of that panel to the manufacturer is probably no more than $350-400. To manufacture and market that PV panel the manufacturer had R&D costs, amortized costs to build manufacturing plants, O&M costs, costs of materials, insurance, labor/salaries, taxes, sales & marketing, shipping, etc., etc. Clearly, given all of those costs, it's obvious that the embodied energy is not going to be that significant. Even if $50 of the $350-400 represents embodied energy (which seems high), that still suggests the panel will produce 10x that over its lifetime (and, by extension, offset approximately 10x its embedded carbon).

PV technology and some other renewable technologies have been colored heavily with fossil energy and non-renewable non-recyclable materials so there is a big potential for enron like accounting and I am glad that articles like these are stimulating the minds of those who are sold on solar tech to search the truth. Solar breeder plants (using solar to produce solar materials) have been rare and are still not a closed system. Solar tech as it presently is looks unsustainable.

Yes there is plenty of energy from sun, but it is spread out in comparison to what nature did in concentrating a lot of this over millions of years to create fossil-fuels. The game from fossil fuels to solar is about integrating sunlight over reasonably large areas and large time to a large area and smaller time, the large area challenges us in terms of the gear for capturing and concentrating light (which is minimal for fossil, it is essentially just drilling a hole and getting out nearly ready to use high density energy) and the small time challenges us in terms of storage technologies, which in turn require energy, thus lowering the net return on energy (if at all positive).

The solar technologies that are more likely to be sustainable are biology based or solar thermal. A lot of research and lab work should be done to find real answers on net energy and sustainability of solar tech before deploying on a large scale, otherwise it will be sunk investment in comparison of more impactful solutions like conservation and curtailment and lifestyle changes.

Also, large energy consumers like chip manufacturers and solar panel manufactures, buy electricity at bulk prices. Their effective cost is closer to $0.04-0.06/kWh, depending on jurisdiction (some are cheaper, even down to 3c/kWh).

No one here is looking at this the right way. Let's keep all the scientists and the FANCY bogus studies out of it!!!
www.nofreewind.com for numbers.
It's now 2011 and a 3MW solar plant is going up near my house in Pennsylvania at a cost of 18 million dollars. At about 13% output here in the NE it will produce 3.4 million kWhrs per year. If we take a loan at 6% on the 18 million dollars for 25 years it will cost 42 cents per kWh.
Also, I have a proposal for an industrial rooftop installation in front of me. It is rated at 182kW's at a cost of 1.2 million dollars. Take a loan at 6% for 25 yrs and the cost per kWhr is 48 cents. That is all wholesale w/o hookup costs nor maintenance. Also the larger installation does not take into effect new transmission lines.
That's all wholesale. We know a grid can buy coal at 5 cents per kWhr and nat gas for a little more, maybe 8 cents per kWhr. Those numbers include both capital costs to build the power plant and fuel costs. Solar is at least 6 times more expensive. What needs to be considered is how much of that 42 or 48 cents per kWhr is spent on "energy" and how much on labor. This is simply an impossible calculation, you would need to consider gasoline costs for workers to get to their manufacturing/mining sites, transportation costs, sales and marketing(there is lots of that!) and even extraneous costs like what NGO's and Gov't agencies spend to market this VERY expensive electricity which makes people (foolishly) think this is something they would want. o
Energy spent per GDP is 8-10%, so we would have to think the energy used to create these panels could be 5 cents per kWhr.
Now of course that assumes interest rate of 6%, cost drops in half with no interest to around 22 cents per kWhr. So maybe?? energy used is only about 2 cents per kWhr. But don't forget to factor in all those IPCC conferences and thousands and thousands of global warming papers, and billions of dollars spent worldwide on this whole subject of global warming and alternative energy.
Nope, solar doesn't pay whatsoever, not by any standard!

You guys comparing Solar PV to coal, Natural Gas and other fossil fuels are seriously underestimating the value of Solar PVs. You can't compare Solar to coal or Natural gas based upon the cost per KWH because Solar has a unique property that neither of those energy sources have.. You can install solar panels just about anywhere and they produce the most electricity during peak hours. Electricity is not just $0.12, $0.08 kwh like you think it is. To a utility company, electricity produced during the day has a far greater value than electricity produced late at night on a weekend. You would see the true cost of electricity if everyone was put on time of use since that more accurately reflects the cost to the utility. It's not easy to add capacity especially capacity that is only needed during peak hours since it will be completely unused during non peak hours. Coal and Natural gas also cause global warming which a lot of people seem to be glossing over. PV panels made today have an energy payback period of about 18 months now so the point about panels using about the same amount of energy to make as they produce is no longer true. Finally, the point about panels efficiency being low is only partially true.. The article implies the highest efficiency economically viable panels have an efficiency of only 14%.. That's not true as there are economically viable panels that are now being sold with efficiencies as high as 22% now, therefore decreasing the time it takes for the panels to pay for themselves.

Another way to look at is is cost come down when production goes up. Everyone complains that more people need to buy and use solar panels so that cost of production will be reduced.

I remember reading over a year ago that a thin film solar cell company was actually going to power its operations with thin film solar cells.

I found this to be very interesting. The assembly plant was never built. Raise your hand if you have actually been to a PV assembly plant.. hmm I only see my hand.. Ok, keep your hand up if they actually used the product they are making to generate electricity for their assembly plant.. huh my hand went down. I don't know of a single assembly plant that powers their operations with PV cells.

Surely if the company X over produced and used their cells to generate electricity they would be able to lower the cost of production and become more competitive or at the very least have a marketing ploy and say "we like the product so much we use them".

I have seen grocery stores with solar cells, office buildings, schools and colleges... I don't know a single assembly plant to use its on cells. I work on computers, when they break I fix them.. I did IT for a fast food company, when I was hungry I ate the food there. When I worked for a news paper, I actually read the news paper.. When I work for a ski resort, i skied their mountains.

I think it is telling that assembly plants don't practice what they are selling. If you walked into a resturant and asked an waitress what she liked, and she said "oh I don't eat this crap" would you... Now as I said I might be wrong, if you live near an assembly plant feel free to stop by and see if they actually have PV cells generating electricity, and I don't mean one or 2 as a display.. I mean a significant number that offset their energy usage.

That said I am only asking about assembly plants, i am not talking about all the mining and refining stages, god only knows they would never power their operations with PV.

I would love to think there is at least one assembly plant that actually uses PV power...

Embodied carbon is a huge issue. Your calculations saying that in the worst-case scenario solar panels have half the carbon footprint of gas, for example, no doubt doesn't include the carbon footprint of extracting the gas, building and operating the gas power station and transmitting the energy.

Embodied carbon is massive and must be taken into account, but to use it as an argument against renewable tech is ludicrous - examine the embodied carbon of non-renewables alongside it.

Your attention-seeking title distracts from the valid point of this article: we need to ensure solar panels in tech gadgets are recycled well and not put in as 'greenwash' marketing only.

Once more, and first of all: these are not "my" calculations, they are the calculations of researchers trying to prove that solar panels are ten times better than coal plants. The only thing I did was playing with some variables, something they should have done themselves.

Second. If you would also include the carbon footprint of extracting the gas, building and operating the gas power station and transmitting the energy, you also have to do the same for the solar plant. This means: including all the above for the gas or coal that is needed for the manufacture of the solar panels, the energy required for the construction of the solar production plant, and so on. The result would be the same as it is now, since we are comparing both technologies here. What counts is that they are treated in a similar way. Since they obviously wanted to prove that solar is eco-friendly, the researchers would definitely had included the variables you mention if it would have fit their conclusions.

#56 your calculation is wrong: the 25% efficiency is already included in the rated capacity and you've ignored the hours per day of operation.
It should be 0.2kW x 12 hours/day(average over a full year)x 365 days x 25 years. = 31,900 KWh. You might want to include a reduction in efficiency due to really cloudy days, but many cells work under overcast conditions.

Forgive me if these comments were made previously, I didn't have time to read them all.
You state that the CO2 cost of harvesting and producing the solar panels is not listed, yet you don't consider the cost of harvesting, processing, and transporting the fossil fuels we use, which I would believe is more than silicon (but can't be sure).

A point I would also like to make is that organic solar cells would can be produced in a lab, and use no silicon. These types of solar panels while currently less efficient than their solar counterparts offer great potential in their low cost and means of production. However research into these products is discussed little in the media, and receives very little funding.

No one seems to put in the cost of the batteries and dc/ac converters and the costs to manufacture these. Like the Prius, you could run old Land Rovers for years to make up for what it takes to make one.

CO2 is not a poison or a problem, we would die without it. It is plant food

So, we read this whole article, only to find that in the author's worst case scenario, solar panels are still twice as clean as a coal plant!!!!!!! So, how is that "the ugly side of solar panels"???

Secondly, yes, of course the goal is for all industrial processes to use green tech. So it is not a case of "a better scenario would be for the processes used to make the panels to also be green", because that is already the goal in using solar power.

Over time, solar power gets cleaner and cleaner, whereas fossil fuel generation continues to emit more pollution!!!!

An interesting article, and I love this web site...but I disagree with the point being made in the article.

The math in the article is flawed.
If 1 square meter of solar panels carries "at worst" a burden of 314 kg of CO2 from its manufacturing process and produces "at worst" 900kwh of electricity, that is 348 grams of CO2 per kWh. But what the author conveniently forgets to remind us is that the 314kg is the TOTAL CO2 attributed to the 1 sq-m of panel over its 30 year lifespan. It doesn't produce 900kWh total. It produces 900kWh annually. So over 30 years, 348g of CO2 becomes 11.6 grams of CO2 per kWh. It's easy to skew the facts against solar panels when you forget to ANNUALIZE the 314 kg from their manufacture.
I'm all for the right solutions to the problem. But we won't find the right solution if people don't do their math properly.

The figures you refer to give the total CO2-emissions per square meter of solar panel, regardless of their energy production. Nowhere in the article do I use this figure to arrive to the conclusion that a solar panel costs "348 grams of CO2 per kWh". You are seeing things that are not there.

The second part of the article deals with CO2-emissions per m2 per kWh, but these figures are exclusively based on the data of the researchers, not on my calculation above. I have simply changed their basic assumptions - solar insolation and life expectancy - to come to these results.

Thanks for digging this up, for the analysis, and for the exchange of comments.

Regarding thin-film lifetimes and warranties: The fact of a warranty is very far from proof of lifetime.

That of course is a simple matter of logic. Worse, my impression is that manufacturers will give the warranty needed to sell the product. The company is unlikely to be around in 10 years, let alone 30. The pattern in management today is based on getting loans to get them jobs and stock. All they need to do is drive up stock value, cash in and get out.

Amen, Christian Sweningsen. Both the original author and commenters operate from the assumption that if the items are warrantied for 20 to 25 years, then they must have a 30 year life expectancy. That is naive and absurd. How many home users will monitor panel output for more than ten years, remember where they purchased the panels, be able to locate the manufacturer, still be able to locate their purchase receipt, and be willing to go through the hassle of requesting a refund? The marketing value of a long warranty far exceeds any possible cost of honoring such a warranty. I can't find any independent study that comes anywhere close to those numbers. If you know of one, I'd love to see the link.
I'd also quibble with the argument that those in an industry are always biased and those in academia are always objective. Lots of university professors are bought and paid for by industry.

I love the concept of this article, it addresses my think spot on. Good thing it's still in favour of getting panels!

Although I would also be interested in the carbon emissions in retiring the panels after 30 years and what we do with the waste?

As a last thought: I don't think I will live in my current house for another 30 years, so I would be buying them to increase the value of the house as well. From a fincancial aspect, I really don't care whether they last for 20 or 30 years. So if the manufacturers and we (ok... I ...) the consumers don't care, I think we are in deep problems!

I'm not too naive to think that solar panels will fix our energy problems. However, every dollar invested into this market will bring the solution a little bit closer.

If you are talking about making of a solar cell puts off green house gases when produced, I would like to enlighten you about how a coal/natural/trash power is made. (I build these for a living) First the ore is mined for steal/stainless/nickel then these products have to be melted down and turned into tubes these tubes must be welded into a header (ie my part) then casing framework and installation in the field have to be done.(more welding) Welding uses alot of energy and puts off all kinds of crap that i dont believe anyone knows what gases are being put off when you melt metal to metal inconel and stainless most of all.

this whole article is mooted by the fact that solar cell technology is still in the beginning stages of development. things will presumably change a lot.

what you don't write about is the feedback loop. if you buy energy intensive solar cells today, you are making an investment in the revenue stream which supplies research and development for more efficient.

if people hadn't bought lesser efficient combustion engines, there would not be the more efficient engines we see today.

An interesting read, thanks for that Kris de Decker. Well done in how you deal with those comments from people who haven't had the courtesy to read your article properly. It is informative and rightly reminds us to question conclusions put out by 'researchers'. Thanks - I do appreciate the time you have taken to put this together.

Carbon Footprint of modern solar panels is around 30g/kWhr.
Remember that every kWhr produced by solar displaces a kWhr produced by coal or gas.
That is a huge effect.
And also remember that if you install or support solar on your house or neighbourhood you will have a multiplier effect around the world. Ontario is installing panels, because German's did, and Spanish before them. So feel really good about putting those ugly panels on your roof.
Hghi efficiency solar panels in the US can be purchase for as low $.65/W now. Or about $120 for a 250W panel. Silicon panels are cheaper than thin film. Much higher power.
The revolution has begun!

79 makes a great point. The article is an excellent attempt at determining what the CO2 production is of solar technology, however it does not seem to employ the same rigor in determining what the true CO 2 production of fossil fuels is. Perhaps, the calculation used below from the article include such a cradle to grave analysis, but it is unclear -
"According to the researchers, producing the same amount of electricity by fossil fuel generates at least 10 times as much greenhouse gasses. Checking different sources, this claim is confirmed: 1 kilowatt-hour of electricity generated by fossil fuels indeed emits 10 times as much CO2 (around 450 grams of CO2 per kWh for gas and 850 for coal)".

Mr. DeDecker was such a cradle to grave analysis used in the above quote. If not the solar power analysis is unfairly biased against solar power.

@ Bill (#84): Yes, such a cradle-to-cradle analysis was used in the quote you mention. I have answered this question a couple of times already, please read the comments before you make a new comment.

@ Luke (#83): You write: "Carbon Footprint of modern solar panels is around 30g/kWhr."

Such a statement makes no sense. It all depends where the solar panels are made. I quote from a research paper published in 2010 ("Towards real energy economics: energy policy driven by life-cycle carbon emission", Energy Policy 38):

"One can note that the carbon intensity of China at 788 g/kWh is greater than that of Canada at 184 g/kWh. (...). The most effective carbon-mitigating PV cell would be produced in Canada and sent to China. The low carbon intensity of the electric grid in Canada and corresponding low embodied carbon of the cell would combine with the high mitigation potential in China to produce an optimized mitigation technology."

Unfortunately, it is the other way around. Solar cells are produced in China, and shipped to countries with relatively clean electric grids.

Commenting on an article that is 5 years old and then saying that its numbers are obsolete is a bit lame, isn't it? Of course, the numbers would be different today. Don't expect them to be better, though. The difference with five years ago is that most solar cells are now produced in China, which makes their production more carbon intensive. See comment #85

Interestingly enough, the guaranteed life expectancy of a solar cell is about twice as long as the article claims. The first solar panels that were created by Westinghouse in the 60s are still operating at >80% efficiency. Maybe obsolete isn't the right word. I'd say the correct term is skewed, but I'll give the author the benefit of having written this over 5 years ago.

What is important is the non-subsidized payback period of the entire solar plant and not just the solar cells. Most installations require, solar panels, charge controllers, battery banks, and inverters to work. The actual long-term energy costs of the entire plant is what matters.

They need far more COPPER or ALUMINIUM to transmit power to the users and factories, since they are more widely distributed for the same power production as, say, a nat gas plant.

Further, installing a solar farm, is like CLEAR CUTTING a piece of land since ALL the natural vegetative ground cover ( except that which sprouts in the accumulated dirt on untended panels ) is starved to death in the shade of the panels. Ecologocically, it is utterly disruptive. And these plants would have acted as a carbon sink.

Finally, you have to include the carbon cost of maintaining the solar farm. It isnt zero to have wash the surface dirt off panels and clear away the weeds that are reaching for the light between rows of PV panels abd do electrical maintenance. IF batteries are used, then they have to be tended and tested.

Regarding photovoltaics on gagetry.. My father has an hand-held scientific calculator with a tiny solar cell. The internal battery is gone yet it is both useable and used in daylight or under a bulb.
It is almost 20 years old, and will not need another one.
That tiny PV cell saved a lot of energy for new batteries or new handheld calculators.

For rechargeable ones, how many phones, tablets, laptops are thrown only because baterry became unuseable and a replacement is half as expensive as the laptop itself? If life of these gadgets is delayed with say 10% by having a PV cell that helps battery life, then it effectively saves 10% of all the energy embeded in making another laptop or phone.

It's true that it's hard to count these indirect savings, but it's also unfair to discount them in the equation of how much energy actually saves a PV cell attached to a device.

Good article but was a bit short on the calculations as the Panels are not all that is required to consider the energy and byproducts from the production of the cells... You have to also include the CO2/energy budget for the steel for the mounts and batt racks, the copper for cables, Switch gear, inverters and Battery plants.... Once you add the Totality from mine to end of life and include the energy to clean and maintain the systems you are actually producing Far More CO2 and using Far more energy that you save with panels not to mention the nasty byproducts and materials that will find their way into landfills and the environment wen the systems are trashed out...

I think the following calculations also need to be taken into account:
1. Besides solar insolation, dust, bird droppings, smog, all tend to reduce power consumption.
2. Toxic waste from solar cell factories have to be shipped hundreds or thousands of kilometres away. The transport uses fossil fuels. This should be added to the carbon footprint of the solar cells.
3. The cost of transportation to the place of installation and its greenhouse footprint has to be taken into account.
4. The total installation cost of the solar panels has to be taken into account. I believe that this has not changed very much despite dramatic falls in the cost of the solar cells themselves, because the cost of the solar cells are but a small fraction of the total installation costs.
5. The cost of batteries and inverters have to be taken into account, both in terms of money and environment.

In short Solar panels are ugly, but its a side that no environmentalist or media person wants to see.

"A better strategy would be to use already available solar panels to produce more solar panels"

Nope. Any solar panel connected to the grid improves the performance (in terms of CO2/kWh) of the whole grid, dedicating solar panels to making more solar panels is neither an improvement nor a detriment. It makes solar panel production look better, at the expense of making all other electric uses look (slightly) worse. What really matters is total CO2 into the atmosphere, and that is exactly the same.

Some ways to actually improve the performance include, installations with smaller amounts of infrastructure, installations which consume all the power locally, and installations in high sun areas.

I saw an interesting point in SuperFeakonomics -- solar panels are black so while converting only a small proportion of photo energy to electricity the rest becomes heat that contributes to global warming.

When you post an article, say, "The Ugly Side of Solar Panels", that title chosen no doubt to get page hits, please remember that FOX News and the Fat Man (Limbaugh) and the Teathuglican moronic Christianist sheeple in Congress can all read, albeit poorly, and they will use your article for stupid talking points.

"I saw an interesting point in SuperFeakonomics -- solar panels are black so while converting only a small proportion of photo energy to electricity the rest becomes heat that contributes to global warming."

Sigh... Doesn't work like that. Are you actually saying that painting something black will generate heat? Oh goodness...

Well then, in the fall, let's paint all houses and buildings in colder climes black. They'll generate their own heat and won't need furnaces.

Everyone is welcome to read Low-tech Magazine. If I'm preaching outside my church, all the better. If they use my article to support their views, they will have to refer to it, and if they refer to it, their supporters will be confronted with facts and opinions that will surprise them.

Why would it make any difference if you are using solar energy to create solar panels and not just using it to power the grid in the most optimal locations? Seems like the only important factor to reduce CO2 is to put them where there is a higher density of solar energy.

My limited knowledge gives me the opinion it is a waste of the Earth's resources to put solar pv systems in sub optimal places. Maybe there are factors that aren't so obvious.